The long term goals are to identify the changes in the program of cellular gene expression induced by the 12S gene that results in primary-epithelial cell immortalization and the mechanism(s) by which they occur. Knowing how a cell becomes immortalized is important for our ultimate understanding of the multistep conversion of a normal cell to the tumorigenic transformed phenotype. Although most human neoplasms are of epithelial origin, very little is known about their transformation. Since the 12S gene specifically affects this cell type, it provides a means to study then progression at the cellular and molecular level. Much is known about the first exon of 12S, therefore the investigator will concentrate on the second exon, whose expression is also required for immortalization. The investigator will perform a detailed genetic analysis of the second exon to determine which region(s) and function(s) are important for immortalization. Cellular genes whose expression is modulated by the presence of this region, will be identified.